This invention generally relates to a method and apparatus for recording and reproducing a control signal on and from a magnetic recording tape for use with a video tape recorder having at least one rotary head.
In a video tape recoder having at least one helical-scan type rotary magnetic head, a fixed or stationary magnetic head is provided for recording and reproducing a control signal on and from a magnetic recording tape. The control signal is recorded by the stationary magnetic head along the moving direction of the tape on one edge thereof prior to recording a video signal. The control signal recorded on the tape will be reproduced before the video signal is picked up by the rotary head or heads so that the rotation and the movement of the magnetic tape can be accurately controlled in accordance with the synchronous information derived from the control signal reproduced by the stationary magnetic head.
In most home-use VTRs using half inch width tape, the control sigal track occupies a width of 0.3 to 0.75 millimeters along its longitudinal edge so that the control signal is not superposed upon video and audio signal tracks. Therefore, the control signal is apt to be dropped out due to undesirable waving or shifting of the magnetic tape in the transverse directions. Since the control signal plays an important role for accurately positioning the rotary head on the recorded tracks on playback, dropout of the control signal will result in poor quality of the reproduced pictures.
In addition to the rotary magnetic head and the stationary magnetic head for recording and reproducing the control signal, conventional VTRs comprise an erase head and an audio head which are both stationary. The erase head is used to erase prerecorded signals prior to recording new video and audio signals and a control signal on a magnetic tape. The audio head is used to record and reproduce audio signals associated with the video signals. Namely, conventional VTRs have three fixed or stationary magnetic heads in adddition to the rotary magnetic head. These three stationary magnetic heads are located in the vicinity of the rotary head drum, and therefore, the structure around the rotary head drum is complicated.